Magnetically controlled electron discharge device



p 1936. H. E. HOLLMANN 2,054,126

MAGNETIGALLY CONTROLLED ELECTRON DISCHARGE DEVICE Filed June 27, 1955 INVENTOR HANS ERlCH HOLL MANN ATTORNEY Patented Sept. 15, 1936 MAGNETICALLY CONTROLLED ELECTRON DISCHARGE DEVICE Hans Erich Hollmann, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application June 27, 1935, Serial No. 28,645

In Germany July 5, 1934 4 Claims.

My invention relates to electron discharge devices intended for generating very high frequency oscillations and it is the principal object of my invention to provide improved cooling means for such devices. v

As is well-known the so-called magnetron, particularly the so-called split anode magnetron in which the anode is divided into two or more segments, is an excellent generator of ultrashort and micro-waves. The phenomena occurring in the tube resemble those of the Barkhausen arrangement employing a retarding field circuit except that the electrostatic retarding field of the anode is replaced in the magnetron by the axial magnetic field.

The efficiency of the magnetron is considerably improved if the electrodes are tuned to the frequency of the oscillations to be produced because the resonant voltages arising at the electrodes will then react with greatest effect upon the electron movement to produce the oscillations. Resonant voltages on the electrodes at high frequencies are desired, and this in turn necessitates minimization of electrode capacity. The electrodes, however, should not be made too small for this would decrease the useable power or output of the magnetron. The two anode segments are each provided with wire leads which extend in both directions from the anodes and terminate in parallel wire systems regardless of whether the latter are short-circuited at the ends or connected with a load.

The load capacity of the magnetron is governed principally by the permissible maximum temperature of the plate segments and by heat exchange or equalization. In order that the energy loss dissipated by the anode may be increased, thereby increasing the useable power, I provide in the preferred form of my invention an arrangement wherein the parallel wire leads supporting the two anode segments consist of small diameter tubes thru which a cooling liquid or gas flows. The advantage residing in this novel arrangement over the cooling methods in general use in radio frequency work and in which the cooling liquid or fluid is in direct fiowing contact with the anode resides in the fact that the cooling is eifected without any incidental impairment of the oscillations of the parallel wires and the electrodes, and without causing any dielectric losses.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection withthe accompanying drawing'in which Figure -'1 is a perspective view of' one form of an electron discharge device embodying my invention, and Figure 2 shows a modification of the electrode and support shown 'in' Figure 1'.

In Figure 1 the two anode segments A and A are coextensive with and surround the coaxial cathode K. The coaxial magnetic field is furnished from a magnetizing coil 5. The anode segments are supported by two support and lead wires in the form of Lecher wires L and L which extend lengthwise thru the envelope E of the magnetron and which in accordance with the invention are tubular so that a cooling medium can be circulated thru them. In order that the heat generated thruout the entire anode segments may be dissipated more efficiently by the cooling support tubes, transverse ribs or fins Q are welded fast to the anode segments, incidentally imparting to the latter high mechanical strength.

Under some conditions maximum heating occurs at the edges of the anode segments during operation. In order to compensate for this condition, the cooling action is extended along the V edges of the anode segment. In accordance with a modification of my invention the tube supports M as shown in Figure 2 are provided with parallel branches MM' secured near the edges of the anode B. In order that any small thermal expansion which may incidentally take place may be compensated for to avoid strain at the seals, the tubular leads are sealed at one end in the glass wall of the magnetron tube as shown in Figure 1 by two bellows-like members K, K which may be of glass and which are sealed to the tubes at one end and to the glass envelope at the other. The cooling method here disclosed, of course, is not confined to split anode types of magnetron tubes; it may just as readily be used where more than two anode segments are attached to and supported by tubular Lecher wires or leads in any desired arrangement.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific. application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:-

1. An'electron discharge device havingoan envelope containing a thermionic cathode and a plurality of anodes surrounding said cathode and supports for said anodes comprising tubular members; each of said members extending thru and sealed in opposite ends of the envelope and attached to and supporting said anodes intermediate the ends of said envelope, said tubular 1 ,members providing a path for a. cooling fluid and constituting the leads for said anodes.

2. An electron discharge device comprising an envelope, a straight thermionic cathode within elongated envelope, a straight thermionic cathode within said envelope, segmental'anodes positioned around and coaxial with said thermionic cathode, lead-in and support conductors secured to said segmental anodes and comprising tubular members of small diameter extending thru opposite ends of said envelope, one end of each of said tubular members being sealed directly to the envelope and a bellows member sealed to the envelope and to the other end of each tubular member whereby expansion and contraction of said tubular members can take place in response to temperature changes when a cooling medium is circulated thru said tubular members.

4.-An electron discharge device comprising an elongated envelope, a thermionic cathode within said envelope, segmental anodes positioned around said thermionic cathode, tubular support members for said anodes extending thru opposite ends of said envelope andrprovided intermediate their ends with a pair of oppositely disposed tubular portions secured adjacent the edges of the segmental anodes whereby said segmental anodes are cooled when a cooling medium is circulated thru said tubular support member. HANS ERICH HOLLMANN. 

